What Is the Ankle-Brachial Index?
The Ankle-Brachial Index (ABI) is a non-invasive test that compares blood pressure in your ankle to blood pressure in your arm. It is the primary screening tool for peripheral artery disease (PAD), a condition where narrowed arteries reduce blood flow to your limbs.
A healthy ABI typically ranges from 1.0 to 1.4. Values below 0.9 suggest PAD, and values above 1.4 may indicate calcified or stiff arteries.
ABI Formula
Use the higher of the two arm readings (left/right)
Use the higher of the two ankle readings (per leg)
Interpreting ABI Results
- > 1.4: Abnormal — vessel hardening (calcification)
- 1.0 – 1.4: Normal
- 0.91 – 0.99: Borderline — monitor closely
- 0.41 – 0.90: Mild to moderate PAD
- ≤ 0.40: Severe PAD — seek medical care
PAD Risk Factors
Risk factors include smoking, diabetes, high blood pressure, high cholesterol, age over 50, obesity, and family history of cardiovascular disease. PAD affects approximately 8.5 million Americans.
How to Use
Enter your ankle and arm systolic blood pressure readings. The calculator instantly computes your ABI and provides interpretation.
Why ABI Testing Matters
Early PAD detection through ABI testing can prevent serious complications including heart attack, stroke, and limb amputation. ABI is recommended for patients over 50 with diabetes or smoking history.